The teachings of all the references cited in the present specification are incorporated in their entirety by reference.
Obesity and its associated disorders are common and very serious public health problems in the United States and throughout the world. Upper body obesity is the strongest risk factor known for type-2 diabetes mellitus, and is a strong risk factor for cardiovascular disease. Obesity is a recognized risk factor for hypertension, arteriosclerosis, congestive heart failure, stroke, gallbladder disease, osteoarthritis, sleep apnea, reproductive disorders such as polycystic ovarian syndrome, cancers of the breast, prostate, and colon, and increased incidence of complications of general anesthesia. It reduces life-span and carries a serious risk of co-morbidities above, as well disorders such as infections, varicose veins, acanthosis nigricans, eczema, exercise intolerance, insulin resistance, hypertension hypercholesterolemia, cholelithiasis, orthopedic injury, and thromboembolic disease. Obesity is also a risk factor for the group of conditions called insulin resistance syndrome, or “Syndrome X.”
It has been shown that certain peptides that bind to the Y2 receptor when administered peripherally to a mammal induce weight loss. The Y2 receptor-binding peptides are neuropeptides that bind to the Y2 receptor. Neuropeptides are small peptides originating from large precursor proteins synthesized by peptidergic neurons and endocrine/paracrine cells. Often the precursors contain multiple biologically active peptides. There is great diversity of neuropeptides in the brain caused by alternative splicing of primary gene transcripts and differential precursor processing. The neuropeptide receptors serve to discriminate between ligands and to activate the appropriate signals. These Y2 receptor-binding peptides belong to a family of peptides including peptide YY (PYY), neuropeptide Y (NPY) and pancreatic peptide (PP).
NPY is a 36-amino acid peptide and is the most abundant neuropeptide to be identified in mammalian brain. NPY is an important regulator in both the central and peripheral nervous systems and influences a diverse range of physiological parameters, including effects on psychomotor activity, food intake, central endocrine secretion, and vasoactivity in the cardiovascular system. High concentrations of NPY are found in the sympathetic nerves supplying the coronary, cerebral, and renal vasculature and have contributed to vasoconstriction. NPY binding sites have been identified in a variety of tissues, including spleen, intestinal membranes, brain, aortic smooth muscle, kidney, testis, and placenta.
Neuropeptide Y (NPY) receptor pharmacology is currently defined by structure activity relationships within the pancreatic polypeptide family. This family includes NPY, which is synthesized primarily in neurons; PYY, which is synthesized primarily by endocrine cells in the gut; and PP, which is synthesized primarily by endocrine cells in the pancreas. These approximately 36 amino acid peptides have a compact helical structure involving a “PP-fold” in the middle of the peptide. Specific features include a polyproline helix in residues 1 through 8, a β-turn in residues 9 through 14, an α-helix in residues 15 through 30, an outward-projecting C-terminus in residues 30 through 36, and a carboxyl terminal amide, which appears to be critical for biological activity. The peptides have been used to define at least five receptor subtypes known as Y1, Y2, Y3, Y4 and Y5. Y1 receptor recognition by NPY involves both N- and C-terminal regions of the peptide; exchange of Gln34 with Pro34 is fairly well tolerated. Y2 receptor recognition by NPY depends primarily upon the four C-terminal residues of the peptide (Arg33-Gln34-Arg35-Tyr36-NH2) preceded by an amphipathic an α-helix; exchange of Gln34 with Pro34 is not well tolerated. One of the key pharmacological features which distinguish Y1 and Y2 is the fact that the Y2 receptor (and not the Y1 receptor) has high affinity for the NPY peptide carboxyl-terminal fragment NPY-(13–36) and the PYY fragment PYY(22–36).
It has been shown that a 36 amino acid peptide called Peptide YY(1–36) [PYY(1–36)] [YPIKPEAPGEDASPEELNRYYASLRHYLNLVTRQRY, SEQ ID NO.: 1]. when administered peripherally by injection to an individual produces weight loss and thus can be used as a drug to treat obesity and related diseases, Morley, J. Neuropsychobiology 21:22–30 (1989). It was later found that to produce this effect PYY bound to a Y2 receptor, and the binding of a Y2 agonist to the Y2 receptor caused a decrease in the ingestion of carbohydrate, protein and meal size, Leibowitz, S. F. et al. Peptides, 12: 1251–1260 (1991). An alternate molecular form of PYY is PYY(3–36) IKPEAPGEDASPEELNRYYASLRHYLNLVTRQRY [SEQ ID NO.: 2], Eberlein, Eysselein et al. Peptides 10: 797–803, 1989). This fragment constitutes approximately 40% of total PYY-like immunoreactivity in human and canine intestinal extracts and about 36% of total plasma PYY immunoreactivity in a fasting state to slightly over 50% following a meal. It is apparently a dipeptidyl peptidase-IV (DPP4) cleavage product of PYY. PYY3–36 is reportedly a selective ligand at the Y2 and Y5 receptors, which appear pharmacologically unique in preferring N-terminally truncated (i.e. C-terminal fragments of) NPY analogs. It has also been shown that a PYY fragment having only residues 22–36 will still bind to the Y2 receptor. However, if any of the carboxyl terminus of the peptide is cleaved, the peptide looses its ability to bind to the Y2 receptor. Hence a PYY agonist is a peptide, which has a partial sequence of full-length PYY and is able to bind to a Y2 receptor in the arcuate nucleus of the hypothalamus. Hereinafter the term PYY refers to full-length PYY and any fragment of PYY that binds to a Y2 receptor.
It is known that PYY and PYY3–36 can be administered by intravenous infusion or injection to treat life-threatening hypotension as encountered in shock, especially that caused by endotoxins (U.S. Pat. No. 4,839,343), to inhibit proliferation of pancreatic tumors in mammals by perfusion, parenteral, intravenous, or subcutaneous administration, and by implantation (U.S. Pat. No. 5,574,010) and to treat obesity (Morley, J. Neuropsychobiology 21:22–30 (1989) and US Patent Application 20020141985). It is also claimed that PYY can be administered by parenteral, oral, nasal, rectal and topical routes to domesticated animals or humans in an amount effective to increase weight gain of said subject by enhancing gastrointestinal absorption of a sodium-dependent cotransported nutrient (U.S. Pat. No. 5,912,227). However, for the treatment of obesity and related diseases, including diabetes, the mode of administration has been limited to intravenous IV infusion with no effective formulations optimized for alternative administration of PYY3–36. None of these prior art teachings provide formulations that contain PYY or PYY(3–36) combined with excipients designed to enhance mucosal (i.e., nasal, buccal, oral) delivery nor do they teach the value of endotoxin-free Y2-receptor binding peptide formulations for non-infused administration. Thus, there is a need to develop formulations and methods for administering PYY3–36.